I'm not 100% sure of him to judge but from his performances so far I can analyze the following:
Strengths
Does the simple things
(ball utilization and possession is probably between 70 - 80%
Good in the air
Attacks ball well in both boxes
Will help us keep clean sheets against opposition set pieces
Can grab a few goals a season attacking set pieces.
Works well pressing in numbers
(Pressing triangles with Milner and Barr was great)
Does not over commit or slide into tackles or place himself in potential red card situations.
Will not break forward and leave us sort at the back.
(more important than you think)
Can play a simple pass and doesn't try to over complicate things above his ability.
Helps the team stay strong defensively
(I think we were lucky today though as if the crosses in 1st half were attacked more efficiently by Fulham the outlook on this may have been negated)
He is a likable character (I assume a good professional)
Will not be disruptive if not selected in first team.
Will improve by playing with top quality players
He is not on huge wages
He is only 25 Years old
Can provide cover at CD if we have major defensive problems
(short and long term)
Weaknesses
Limited pace
Limited maneuverability
Limited Technically
Not yet certain what team mates will do yet
(will take time do to fit team)
Puts a few passes astray but all players do
(area of pitch where this happens is a key indicator)
Is not a box to box player
When people say a player purchased for 16M they wish we could have had a player with more options (Felliani, De Rossi, Waganyama) - i.e can play box to box also
Not Clear
Ability to strike a ball
Composure under pressure
How long fans will give him and if he will become boo boy
It has to be said that one of our most important and under appreciated players is Barry and some comparisons could be made. I think we have to be more respectful, look how well Savic is doing at Fiorentina. Patience is the key